The collection of data on downhole conditions and movement of the drilling assembly during the drilling operation is referred to as measurement-while-drilling (“MWD”) techniques. Similar techniques focusing more on the measurement of formation parameters than on movement of the drilling assembly are referred to as logging-while-drilling (“LWD”) techniques. The terms “MWD” and “LWD” are often used interchangeably to refer to the collection of formation and borehole information, as well as of data on movement of the drilling assembly.
Measurements of the subject borehole are important in the measurement of the parameters of the formation being penetrated and in the drilling of the borehole itself. Specifically, measurements of borehole shape and size are useful in a number of logging or measurement applications.